Process of producing decolorizing-carbon



To all whomit may concern n rrsa earns easnr errata.

MILTON B, runnnr'r AND RAYMOND A; WHITAKER, or ROCHESTER, NEW YORK,

' .ASSIGNORS '1'0 EASTMAN KODAK COMPANY, OF

conrona'rron' or NEW, YORK.

nocnns'rnn, NEW YORK, A

. PROCESS orlrnonucme nEcoLoRIznie-cmon.

. 1,383,755. No Drawing.

Be it known that we, MILTON B. PUNNETT and RAYMOND A." WHITAKER, citizens of the United States of America, residing at Rochester, in the county of Monroe and Stateof New York, have invented certain new and useful Improvements in Processes. ofProiof cheapness crude forms are used, such as ducing Decolorizing-Carbon, of ,whichthe' following is a full, clear, and exact specification.

This invention relates to aprocess of making decolorizing carbons. One object of this invention is to produce highly efiicient decolorizing carbons by relatlvely simple and inexpensive operations from cheap ingredients. Another object of this invention is to produce carbon'which will have astrong decolorizing effect on the usual liquids re-. quiring purification, such as sugar sdlutions, glue, oils, organic reducing substances like photographic developers, etc., yet will not interfere with the usual filtering and the like subsequent operations. Other objects will hereinafter appear. 1 Y

We have dlscovered that decolorizing carbons having the necessary qualities can be made by charring' carbonizable materlal (preferably comminuted) such as straw, sawdust, vegetable ivory nuts, cocoanut shells, cohune nuts, residue of nut-gall-pulp paper, etc., in the presencev or adinixtureof sulfate salts of which the alkali metal sulfates, like sodium or potassium sulfate, and sodium or potassium acid sulfate, aHSO, KHSOQ- are typical. The range'of sulfates available includes many different compounds, but for the sake niter-cake contai NaHSO, and' some free sulfuric acid- 80,. After charring, the charred material is separated from the residue of the salt and subjected to a sec- 1 ond heat treatment at higher temperatures K while substantially protected from burning.

-By way of example we shall now describe one of the ways in which our process may be carried out. For the .carbonizable mate rial we may use comminuted vegetable matter of a woody nature, such as hardwood sawdust.

To approximately 100 parts of this by weight there is added 100 parts of an aqueous solution containing 75% nitercake. The latter is composed chiefly of so-' dium hydrogen sulfate together with some pecificatio1i of Letters Patent.

Application filed May 12,

4 Patented July 5, 19210 1919. serialm. 29%;,370. I

free sulfuric acid which is ordinarily left 1n the cake during the manufacture of nitric acld, 1n order to make the cake readily. removable. This sulfuric acid does no harm and in fact may take a distinct part in the I preferred process. Sincethe niter-cake and the sawdust are both normally waste products, it will be seen that the ingredients are very inexpensive.

The sawdust should take up practically all of the solutlon, the amount of solution being regulated accordingly and the above proportlons belng merely illustrative. This mixture is allowed to stand for several hours, two hours belng sufficient in some in-.

stances, although the time may be prolonged .to twentyfour hours without injurious F effect.

6 After standing, the mixture is heated in an open retort in-fcontact with the air to a temperature between 300 C, and 500 C. until the mass is completely charred' Such charrmg will ordinarily take place in from one-half to one'hour, and the end point is convenlently indicated by the fact that the evolution of sulfurous fumes is diminished or substantlally ended. During the charring operation the mixture may be in thin layers and should preferably be stirred at frequent intervals.

The charred mass, when sufiiciently cooled to permit of such operation, is stirred into Y the least amount of water that will dissolve the sodium sulfate or other salts resulting from the original miter-cake. This watery mass is then heated to boiling and filtered, thereby separating the charred material from the salts. If desired, the filtrate may be evaporated and the salts recovered by crystallization, but sucli an is, of course, not necessary. I

The charred and purified material is then auxiliary step dried ,in any preferred way and then finely ground.

Finally the purified and ground, dried, charred material is heated in a closed retort to. a temperature ,above 700 C., the

preferable range'of temperature being from 800 C. to 1000 C. This second heating under non oxidizin'g conditions or in substantial freedom from contact with the air is generally completed in from 20 to 30' minutes. The material should be sufliciently cooled before the retort is opened and the I When straw s used as the comminuted vegetable material, whicli'is carbonizable, it is cut into pieces, say one inch in length. It is then put into a sulfate solution'made up with a weight of niter-cake equal to seven I times the weight of straw in an equal weight of water. This may stand over night and the straw then be filtered of. The resulting .mass is then treated in the sameway as the sawdust mixture hereinabove described. This product is excellent. v

By a generally similar method useful care bons having varying degrees ofdecolorizing power may also be made from coc'oanut.

shells, cohune nuts, vegetable. ivorynuts,

' paper, the nut-gall-pulp resulting from the manufacture of pyrogallic acid, etc.

While we have hereinabove disclosed cer tain ingredients and steps by way of exemplifying our process, our invention is Irot limited thereto nor to the precise proportions given therein, our experiments indieating that the proportions and temperature ranges may be considerably varied and equivalent ingredients may be substituted without departing from the principle of our invention as defined in the appended claims. I, w

Having thus described our invention,

. ing carbon the step of heating a mixture of what we claim as new and desire to secure by Letters Patent is:

1. In the process of producing decoloriz= ing carbon the stepof charring by heat car bonizable but uncarboni zed material in the presence of an acid sulfate salt present in substantial quantity when said charring hes gins. 4

2. In the processof producing decolorizcarbonizable but uncarbonized material and anacid sulfatesalt open to the air to a temperature between 300 0. and 500 C.

'3. In the process of producing decolorizing carbon. the step of charring by heat comminuted vegetable matter in admixture with added sodium acid sulfate.

4:. In the process of producing 'decoloriz;= ing carbon the step of heating anintimate mixture of comm'muted vegetable matter and sodium acid sulfate to a temperature between 300 C. and 500 Cfuntil there is a substantial cessation in the-evolution of fumes.

.5. "in the process of producing decoloriz ing carbon the step of heating in thin layers i open to the air wlth stirring an admixture asserts 'terial out of contact withthe air acid sulfate salt, drying said matter 'with the salt admixed therein, a nd heating the mix- "ture to a temperature between 300 C. and

500 C. p 8. In the process of producingdecoloriz ing carbon the steps of absorbing in -comtemperature of from 300 C. to 500 C. until the evolution of sulfurous fumes substanmlnuted vegetable mattera concentrated solution of sodium acid sulfate, drying, and heating to a temperature between 300 C. and 500 C. until the evolution of fumes substantially ends.

9. In the'process of producing decolorizing carbon the steps of treating hardwood sawdust with. a strong solution of .nitercake, drying, and heating, while 0 on to the air, to a temperature'below 500 until the evolution of sulfurous fumes substantially ends.

l0. The process ofproducing decolorizing' carbon which comprises charring carbonizv able material .m'the presence of an acid sulfate salt, separating the charred material from said salt, and heating the charred ma-' to .a temperatureabove700 C.

11. The processof producing decolorizi'ng carbon which comprises mixingv the carbonizable'material with an acid sulfate salt 500 C. to carbonize the material, separating the carbonized material from the salt and heating .the carbonized material substantially out of contact with the alr, to a temperature above 7 00 C.

12. The process of reducing decolorizing carbon which co'mprlses intimately mixing commimited vegetable matter and sodium acid sulfate, heating the mixture open to the air to a temperature between 300 C. and

500 C. to carbonize the matter untilfithe evolution of fumes substantially ceases, separating the carbonized matter from the residue of said sulfate and heating said car bonized matter to a temperature between 700 C. and 1000 C.

. material with a solution of an acid sulfate substantially out of contact with the air.

salt, drying the mixture; charring the car- I bonizable material in the mixture, washing the residue of said acid sulfate from said 65 of hardwood sawdust andniter-cake to a charred materiahdrying saidcharred ma 105 I heating the mixture between 300 0.. an I terial and heating said charred material under substantial non-oxidizing conditions to a temperature above 700 C.

,14. The process of producing decolorizing carbon whlch comprises absorbing in comminuted vegetable matter a strong solution of sodium acid sulfate, drying and heating the mixture to a temperature between 300 C; and 500. to char said matter, washing from the mixture the residue of said sulfate, drying and heating the charred matter to a temperature between 800 C. and 1000 C. substantially out of contact with the air.

15. The process of producing decolorizing carbon which comprises impregnating comminuted vegetable matter with a strong solution of niter-cake, drying and heating the impregnated matter until the diminution of fume evolution indicates that the matter is charred, dissolving out the salts from the charred matter, and heating said charred matter under substantially non-oxidizing conditions to a temperature above 700 C.

16. The process of producing decolorizing carbon which comprises adding to 100 parts of hardwood sawdust 100 parts of a 75 per c'ent. aqueous solution of niter-cake, allowing the mass tostand. from two to twenty-four,

hours, drying and charring the mass by heating it open to the air-in thin layers with stirring to a temperature between 300 C. and 500 C. for one-half to one hour, cooling, addinga small enough amount of water to dissolve the sulfate salts, boiling and filtering, drying the charred residue, grinding the charred residue, heating the charred residue to a temperature between 800 C. and 1000' C. in a closed retort, cooling until said charred residue will not ignite in the air and grinding said residue.

17. The process of producing decolorizing carbon which comprises charring the carbonizable material in the presenceof an acid sulfate salt, separating the charred material from said salt, grinding the charred matestantially out of contact with the air to a temperature over 700 C.

18. The process of producing decolorizing I carbon which comprises intimately mixing comminuted vegetable matter and sodium acid sulfate, heating the mixture to char the matter, separating the charred matter from the residue of said sulfate, grinding the charred matter, heating the charred matter to a temperature between 800 C. and 1000 C., and grinding said charred matter.

19. In the process of producing decolorizing carbon the step of charring by heat carbonizable but uncarbonized material while open to the air in the presence of an initially present sulfate salt.

20. In the process of producing decolorizing carbon the steps of mixing carbonizable but uncarbonized material with a solution of a sulfate salt and drying and charring the carbonizable material in the mixture while open to the air. 7

21. The process of producing decolorizing carbon which comprises charring carbonizable material in the presence of a sulfate salt while open to the air, separating the charred material from said salt and heating the charred material substantially out of contact with the air to a temperature above 700 C.

22. The process of producing decolorizing carbon which comprises mixing carbonizable material with a solution of a sulfate salt, drying the mixture, charring the carbonizablematerial in the mixture while open to the air, washing th residue of. said sulfate from said charred material, drying said charred material and heating said charred material under substantially non-oxidizing conditions to a temperature above 700 C.

' Signed at Rochester, New York, this 9th day of May, 1919.

' MILTON B. PUNNETT.

RAYMOND A. WHITAKER, 

